Hatcher Pass

Numerous large D2-2.5 avalanches occurred as a result of the 4/11-13 Passover Miracle Avalanche Cycle that dumped 30″+ of new snow with approximately 2.8″ SWE at 3550′ and likely more snow above 3500′. Most of the avalanches were storm slabs with a few wind slabs and failed in the new snow/old snow interface. However, some avalanches failed deeper within persistent weak layers. See more under persistent slab problem in the forecast.

Avalanches were observed in the following locations (have not observed IM bowl yet): Marmot 1/Vice Presidents, Marmot 2, Marmot 3, Seldom scene, Frostbite, Knob point above Goldmint, Idaho Peak, Archangel 1/Firn, Archangel 2, Punk Spines, to name a few.

Idaho Peak and Divide Ridge sluffs and recent slab avalanches. Look closely at the gullys that are all filled with debris from the 4/11-13 avalanche cycle. Photo: Jed Workman

4.12 Naturals from 4/11-13 avalanche cycle, Vice Presidents, Marmot 1,2. Debris can be seen crossing the road in the lower right from Marmot 1 gully. Photo: Jed Workman

Marmot 3 gully with avalanche debris from two paths crossing the road. The was one of two paths that closed the road on Friday as a result of the 4/11-13 avalanche cycle. Photo: Jed Workman

Close up of the large avalanches on Vice Presidents ridge in Marmot gully 1. These avalanches filled the gully with debris and covered half the road. Photo: Allie Barker

Recent slabs on 4068′ and a large slab in the back of Valley of Sin, scroll in! This crown encompasses nearly the entire face of peak 4500′ N thru SE aspects.

Recent avalanches with visible slab avalanches and crowns on lower 4600′ and Government Peak. NE 4400′ NE 4000′

4/12 Debris can be seen filling the gully from Frostbite ridge. Look closely middle left of the photo to see the debris.

Persistent slabs 1 to 3 feet thick will be possible to human trigger on all aspects, at all elevations, on slopes steeper than 35º. Remotely triggering an avalanche will be possible today. Natural avalanches are unlikely.

There are specific and isolated locations where triggering a small to large avalanche is still possible. Picking out exact problem locations will be difficult. The most likely location will be where weak sugary snow/facets are buried and sitting on top a firm bed surface, either an old wind slab on leeward aspects or a sun crust on southerly aspects in a shallow location.

On Thursday, a skier remotely triggered a persistent slab from several hundred yards away which ran 800 ft.

4/13 The Knob above Goldmint. 2800′ WNW, remotely triggered slab avalanche. See slab in middle lower left of the photo with debris running approx 800ft.

Most of the recent avalanches that occurred as a result of the 4/11-13 storm were storm slabs with a few wind slabs and failed in the new/old snow interface approximately 12″ to 24″ deep. Most of these avalanches went mid-storm or towards the end on 4/12 and the crowns can be hard to pick out several days later. On Friday, we observed numerous large slabs on all aspects, at all elevations. More info is in the avalanche section. We did not have propagation in our pits on east and north aspects Friday but did find buried facets sitting on old firm wind slabs.

4/12 Divide ridge and Idaho Peak , old wet loose and recent slab avalanches failing on firm faceted crusts SSE 3200′

Expect the persistent slab problem to continue to heal slowly throughout the spring before it transitions into a wet slab problem as temperatures increase and cease to freeze overnight.

Pole/probe tests and formal stability tests will help you identify this problem. Whumping and shooting cracks will be red flags for this avalanche problem.

If you head into avalanche terrain today, utilize strict safety travel protocols, travel one at a time from safe zone to safe zone, only have one person on slope at a time, ensure all members of your party are carrying and know how to use beacons, shovels and probes, and avoid slopes with terrain traps.

Temperatures are starting out significantly warmer this morning with only a slight freeze at low elevation. At 5am this morning temperatures are 31º at 2700, 27º at 3550′ and 22º at 4500′. Expect moist snow surfaces to cling to your boots and skins making uphill or downhill travel challenging and catchy in the afternoon. Sunshine is in the forecast for today with temps expected to reach 42ºF below 2500′ and in the middle 30’s which will feel quite a bit warmer above 4000′. Despite the lack of sunshine this week (month, season…put in your own noun here ) intense radiation ie. greenhousing from the clouds has transformed snow surfaces this week, surprising even the most seasoned locals. Finding low density powder will be a challenging scavenger hunt with little to no reward unless you are very motivated.

Looking forward: Pay attention to rapidly changing springtime conditions.

As spring progresses and the temperature warms up, expect avalanche danger to change. Once it ceases to freeze at night for approximately 3 nights in a row, pay attention to and keep a lookout for wet avalanche problems. This might not happen until May, but it is on our radar.

Avalanche concerns in the spring can become complicated.  Four concerns to be aware of include:

1.Loose Wet Avalanches- Loose wet avalanches are typically the first avalanches we see as the snowpack warms up. They can be triggered by snow heating up especially near rocks and cliffs on steep slopes.  While they are relatively small and manageable on their own, they can be dangerous if they pick up enough volume, or if they push you into terrain traps. They can also trigger larger slab avalanches as they travel downhill. They are typically preceded by rollerballs or pinwheels rolling down slopes as they heat up. This in an easily avoidable avalanche problem.

2. Wet Slabs – Wet slab avalanches occur when meltwater from rain or warm temperatures percolate down through the snowpack and weaken the bonds (strength) of a buried weak layer. These avalanches can be human-triggered, but also occur naturally, including triggering from a small, wet-loose avalanche or cornice fall.  Colder temperatures should lock up the snowpack this morning, but strong sunshine today could provide enough warming to trigger isolated wet slabs. These slabs will be the largest on southerly aspects where firm crust bed surfaces exist.